The present invention relates to Digital Video Broadcasting systems and more particularly to a method and an apparatus for extending the Digital Video Broadcastingxe2x80x94Common Interface function by enabling a direct access to conditional access features.
The environment from which the present invention is derived is the digital video broadcasting (DVB) a detailed specification of which is given in the Standards. One may refer, for instance, to the European Telecommunication Standards Institute (ETSI) relating to the Digital Video Broadcasting published in EN 300 468xe2x80x94v1.3.1 (1997-09). Any other digital video broadcasting specification may be used.
The DVBxe2x80x94Common Interface (DVB-CI) for Conditional Access and Other Digital Video Broadcasting Applications is one of a few consumer hardware interfaces specified by the DVB. It is designed to bring the full benefits of open standardization to the supply of digital reception equipment, whilst at the same time making it possible for the Conditional Access and security elements of a digital TV receiver system to remain proprietary. By using this interface, the proprietary elements of the system can be separated from the parts required to receive and decode digital television and data services. They can be manufactured and distributed separately, releasing the constraints which occur when the elements are supplied together.
One may refer to the European Standard issued in April 1996 by the CENELEC (Comite Europeen de Normalisation Electrotechnique), on xe2x80x9cCommon Interface Specification for Conditional Access and other Digital Video Broadcasting Set Top Box Applications xe2x80x9d. This document aims to describe a common interface by defining the standards that relate to the source coding, channel coding, service information, STU interfaces and a conditional access. This latter is used when there is a need to control access to a broadcast service which is a set of elementary streams offered by the user as a program. According to the document, the application operates in a module, communicating with the host, and provides facilities to the user over and above those provided directly by the host. The host is a multimedia device such as a PC, a VCR or an IRD etc. where modules can be connected. Conversely, a module is a small device, which is not working by itself, but is designed to run specialized tasks in association with a host such as a conditional access sub system, an electronic program guide application module, or to provide resources required by an application but not provided directly by the host. The resource is a unit of functionality provided by the host for use for a module. It defines a set of objects exchanged between module and host by which the module uses the resource.
In this CENELEC document, a solution to the problem for broadcasters to access decoders with different conditional access systems and to ensure that they have choice of supply of such systems consists in using a standardized interface between a module and a host where Conditional Access and more generally defined proprietary functions may be implemented in the module. Consequently, broadcasters can use modules containing solutions from different suppliers in the same broadcast system, thus increasing their choice and anti-piracy options.
Consistency is one of the most important problems to solve for the design of good user interface. To allow a user to understand and to learn a User Interface (UI), it is mandatory that the same concepts be identically labeled all over the UI. This concept consists in using a predetermined format whereas the content of the messages is not compulsory. Furthermore, concerning the organization of the information, it must be conformed with the consistency rule.
With the current approach of the DVB-CI, this purpose is hardly reachable. Different Conditional Access Modules (CAM) refer to similar concepts such as entitlements, tokens, or pay per view, with different names. The way to access the different features is different from one CAM to another. For instance, each CAM provider proposes its own hierarchical menu organization with its own labels. All these differences co-existing in the same STU will necessarily confuse the user. The use of a unique look and feel is not sufficient to avoid the confusion.
It is not realistic to target a Set Top Unit compliant with all the private Conditional Access Application Program Interfaces. In many cases, for a given place, there are only one or two leading Conditional Access systems. Thus, an optimized STU would perfectly answer to the largest market whilst remaining open to minor CA systems even though for these latest ones, it would not offer the optimal User Interface.
It is a main object of the invention to provide a method and an apparatus for providing Conditional Access features to STU as if the CA modules were transparent.
It is thus an object of the invention to offer in the DVB-CI environment an additional method and apparatus for accessing directly the Conditional Access Module in addition to the standardized access by defining a protocol of communications with a predetermined format.
It is a further object of the invention to allow the communication between the Set Top Box and the Conditional Access Module without imposing a predefined content of the communication messages.
The invention is to be used in the Digital Video Broadcastingxe2x80x94Common Interface environment for accessing the Conditional Access Module (CAM). The host application handles objects of the Conditional Access (CA) through a private Application Program Interface (API). Each CAM may have its own private CA API but the data channel remains identical whatever the CAM is.
According to the present invention, a private CA Application Program Interface concept and a standard Application Program Interface concept can coexist together. The Private API is a new mode which coexists with the two already defined modes of high and low Man Machine Interface resource.
If a STU xe2x80x9cunderstandsxe2x80x9d the private CA Application Program Interface (API), then it may access the features of the plugged CA through its private CA API Protocol. Otherwise, it remains on the standard API.
With this extension, a STU can have a Conditional Access User Interface which perfectly fits into the overall User Interface of the STU. Thus, a broadcaster can ensure that its look and feel are respected on its STUs. A manufacturer can build a STU especially optimized for a given CA or a plurality of CAs but still able to run other CAs.
According to the present invention, a method for allowing communications exchange between at least one Conditional Access Module and a user interface of a multimedia device in a communications system by enabling a direct access to said at least one conditional access module, said communication system using a standard application program interface protocol and a private application program interface protocol, comprises the steps of:
transmitting a first message (PCA_identification) from said conditional access module to said user interface containing predetermined parameters, wherein said parameters are dedicated to said private application program interface protocol;
checking if said user interface are conformed to said parameters;
responding with a second message (PCA_identification answer) from said user interface to said conditional access module, said second message containing a result of the matching between the Conditional Access Module and the user interface parameters; and
in response to said second message, selecting said private protocol or said standard protocol.
Furthermore, an apparatus for implementing the method for allowing communications between a plurality of conditional access module and a user interface according to the present invention is disclosed therein.